Means for detecting wear on bits



J. B. WARREN, JR

MEANS FOR DETECTING WEAR ON BITS May 3, 1949.

Filed June 11, 1943 Patented May 3, 1949 UNITED STATES PATENT OFFICE 2,468,905 MEANS FOR DETECTING WEAR 0N BITS John B. Warren, J12, Houston, Tex.

Application June 11, 1943, Serial No. 490,431

4 Claims. 3

The invention relates to a means for detecting wear on drill bits of the type used in the rotary method of drilling wells where the amount of wear upon the bit cannot be detected with any degree of accuracy.

In the rotary method of drilling wells where a drill bit is advanced into the earth by the rotation of the drill stem and a drilling fluid is circulated into and out of the well bore, drill bits have now been provided which drill several hundred feet without being replaced, but wear occurs on the drill bit, both on the bottom cutting blades and upon the side reaming edges. This wear will vary, of course, in accordance with the type of formation being drilled; and in view of the fact that the bit is inaccessible the driller must depend upon his drilling experience to advise him when the bit has been Worn a predetermined amount and that eflicient drilling is not being accomplished.

In many instances where the well is deep it is impossible to determine the amount of wear on the bit. A worn bit not only reduces the rate of drilling, but often results in a crooked hole and a reduction in the hole diameter.

The present invention directs itself to a means for indicating to the driller that his bit has worn away a predetermined amount either at the cutting blades or the reaming edge. In this manner the driller will be definitely advised that a predetermined wear has occurred and he can immediately discontinue drilling and replace the bit. It is, therefore, one of the objects of the invention to provide a drill bit with an indicator material which will be released when a predetermined amount of wear has occurred so that this indicating material may be detected at the surface and an indication or alarm given to advise the driller thereof.

Another object of the invention is to provide an indicator material for drill bits which can be detected at the surface after having been released upon the occurrence of a predetermind amount of wear upon the bit.

Another object of the invention is to provide a drill bit with indicating material which is spaced from the normal cutting edge thereof a predetermined distance so that it will be released when the bit is worn away-such distance.

. Still another object of the invention is to provide a radioactive indicating material to signal that a predetermined amount of wear has occurred upon a drill bit when such material is detected at the surface of the well in the drilling fluid.

. Still another object of the invention is to provide a radioactive material with a means to discharge the same from a drill bit upon the occurrence of a predetermined amount of wear.

Other and further objects of the invention will be readily apparent when the following description is considered in connection with the accompanying drawings wherein Fig. 1 is a side view of a conventional type of fish-tail bit in which has been incorporated the indicating material of the invention.

Fig. 2 is an edge view of the bit of Fig. 1.

Fig. 3 is enlarged broken sectional view through one of the indicating material pockets to illustrate the manner of confining the same.

Fig. 4 is a diagrammatic view of a well being drilled with the present invention in use.

In the drilling of wells by the rotary method, the derrick I is usually provided and a suitable mechanism used to turn the rotary table 2 which grips the drill stem 3 in order to rotate the drill bit 4 at the bottom of the well bore 5.

The bit 4 rests on the bottom 6 of the well and and the rotation of the drill stem causes the bit to cut away the earth formation as the bit advances. In order to carry away the cuttings of the bit a drilling fluid 1 is circulated down through the drill stem, discharged from the drill bit and returns upwardly in the well bore to flow into the slush pit 8 from the return line 9.

The bit 4 is seen in Fig. 1 and includes the body portion l2 which has the threaded pin l3 thereon for connection to the lower end of the drill stem. The body i2 is formed with an internal cavity which terminates in the discharge ports 14, one of which is shown at the front cutting face 15 of each of the blades.

The body as seen in Fig. 2 is somewhat tapered and has a back-up portion l6 which supports the cutting blade N. This blade extends outwardly from the body as seen in Fig. 1 and has a straight reaming edge l8 which determines the diameter of the hole being drilled. The blade I! has the bottom cutting edge 20 which extends transversely of the well bore and serves to cut away the formation as the bit is rotated and some of the weight of the drill stem 3 applied to it. As noted in Fig. 2 the opposite blades are offset somewhat to facilitate the cutting action. This type of blade is generally known as a twoway'fish-tail bit or two-way drag bit.

The present invention has been applied to this generally conventional bit by forming the recess or pockets 22 in the side reaming edges and in the bottom cutting blades. These pockets extend inwardly from the edge a desired distance and as seen in Fig. 3 are adapted to receive thecapsule or container 25 which will carry a suitable indicating material 26 therein. This material may be a radioactive material and it may have confined with it in the container 25 a suitable compressed fluid or gas which may be liquified and confined'with the indicating material under considerable pressure. This is desirable because of the fact that the static pressure of the column of drilling mud 1 creates a considerable static pressure at the location of the drill bit and considerable pressure may be necessary to discharge the indicating material into the drilling mud. As an illustration, a compressed material or explosive might be used which would tend to expel the indicating material if and when the cutting blade of the drill bit wore away to the point 21 soas to release the indicating material.

In order to position this indicating material the desired or predetermined distance from the normal cutting edge 20, when the bit is new a spacer plug 28 has been inserted in the pocket 22 after the insertion of the indicating material and this plug in turn is shown as being afiixed in position by a spot 29 of welding material. It seems obvious that these pockets 22 can be of any desired size, depth or configuration and may be positioned as desired upon the cutting blade or the reaming edge. Fig. 1 shows two such pockets on each cutting blade and each reaming edge.

In actual operation as the drilling proceeds and the material of the bit wears away due to abrasion with the earth's formations eventually the spot 29 and the spacing piece or plug 28 will wear away at the same rate as the material of the bit. When a predetermined amount of wear has occurred the container will be exposed and subjected to wear whereupon the indicating material will be released or discharged as the case may be.

It should be borne in mind that during the drilling operation the drilling fluid is circulating downwardly through the drill stem and upwardly in the well bore to discharge from the pipe 9 as seen in Fig. 4. This indicating material will, of

course, be picked up by the drilling fluid passing the bit and move upwardly in the well bore out through the pipe 9.

In order to detect the presence or passage of such indicating material a suitable indicator 35 has been positioned upon the return line 9. If

the indicating material is a radioactive material,

an instrument operable by the presence of such,

radioactive material may be provided. One such instrument is known as Geiger-Mueller counter and the number of beats or counts rendered by such instrument is proportional to the amount and proximity of a radioactive material. Such counter could be made audible to the driller or could be connected to actuate a suitable alarm or recorder as may be desired, the principal feature being to advise the driller that the bit has been worn sufficiently to discharge the indicating material, that such material has been detected or indicated at the surface. It is then time to change the bit.

It seems obvious that the detector 35 would be of a type suitable to detect the particular indicating material being utilized and that the invention contemplates such variation in accordance with the material being used.

The detector 35 may be in the form of a recorder by which a record of the operation of each bit in the well bore could be obtained.

The indicating material from the reaming edge pockets might be of a different character or type 4 than thatof the released at the bottom cutting blades so as to enable the driller to determine which part of the bit is worn.

an inaccessible location so long as there was present a circulation of a carrier liquid to bring the indications to the recorder.

Broadly the invention contemplates a means for detecting wear on bits which are disposed in an inaccessible position.

What is claimed is:

1. In combination with a rotary drill bit having a cutting blade, an opening extending into the blade, a charge of radioactive material together with a compressed fluid to effect discharge of such material, a wear piece positioning said charge a predetermined distance from the cutting edge of such blade whereby such material is released to indicate that such predetermined wear has occurred.

2. A drill bit for rotary well drilling where the column of drilling mud exerts a pressure on the bit, an indicating material to be discharged into the drilling mud, means on the bit to retain such material for release after a predetermined wear on the bit, and means comprising a compressed material to discharge said indicating material when such predetermined wear occurs.

3. In a drill bit of the character described and otherwise more or less conventional in general form and arrangement, a container mounted on said bit and containing a dischargeable indicating material, a normally inactive discharging element cooperatively associated with said container and adapted when activated to forcibly eject said indicating material from said container, and means for rendering said discharging element active by a wearing away of the drill bit.

4. In a drill bit of the character described and otherwise more or less conventional in general form and arrangement, a container mounted on said bit and containing a dischargeable indicating material, and there being a communicable passage between said container and a closed portion of the bit in the immediate region of the cutting edge portion of the bit, a normally inactive discharging element cooperatively associated with said container and adapted when activated to forcibly eject said indicating material from said container, and means for rendering said discharging element active by a wearing away of the drill bit suflicient to open such communicable passageway.

JOHN B. WARREN, Ja.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,662,429 LoWy Mar. 13, 1928 2,007,465 Burt July 9, 1935 2,206,922 Smith July 9, 1940 2,239,106 Krall Apr. 22, 1941 2,246,812 Pivoto June 24, 1941 2,296,183 Richard Sept. 15, 1942 2,315,845 Ferris Apr. 6, 1943 FOREIGN PATENTS Number Country Date 201,888 Germany 1908 

